Heart murmurs

In addition to tones, additional sounds of longer duration, called murmurs, are often heard during auscultation of the heart. Heart murmurs are sound vibrations that most often occur in the heart when blood passes through narrowed openings. The presence of a narrower than normal opening can be explained by the following reasons:

1. the valve flaps are fused, which results in their incomplete opening, i.e. stenosis - narrowing of the valve opening;
2. a decrease in the surface area of the valve flaps or an enlargement of the valve opening, which leads to incomplete closure of the corresponding opening and backflow of blood through the narrowed space.

In addition, there may be abnormal openings in the heart, such as between the ventricles. In all these cases, there is a rapid flow of blood through a narrow space.

In this case, eddy currents of blood and oscillations of valves arise, which spread and are heard on the surface of the chest. In addition to these so-called intracardiac murmurs, extracardiac murmurs are sometimes determined, associated with changes in the pericardium and the pleura in contact with it - the so-called extracardiac murmurs.

By nature (timbre), noises can be blowing, scraping, sawing, etc. In addition, one should keep in mind noises of higher frequency - musical ones.

Heart murmurs always refer to a certain phase of the cardiac cycle. In this regard, systolic and diastolic murmurs are distinguished.

Systolic heart murmurs

Systolic murmurs are heard after the first tone (between the first and second tones) and arise due to the fact that during the contraction of the ventricle, blood is expelled from it through a narrowed opening, while the narrowing of the lumen of the opening can be in the path of natural blood flow (for example, stenosis of the aortic or pulmonary artery) or when blood moves in the direction opposite to the main blood flow (regurgitation), which occurs with mitral valve insufficiency.

Systolic murmurs are usually more intense at the very beginning and then they become weaker.

Diastolic murmurs are heard after the second tone (between the second and first tones) and are determined when, during diastole, blood enters the ventricles through narrowed valve openings. The most typical example is stenosis of the left atrioventricular orifice. Diastolic murmurs are also heard in case of aortic valve insufficiency, when blood returns back to the left ventricle through an incompletely closed orifice of the aortic orifice.

As can be seen from the examples given, the localization of noise is of great importance in determining the nature of the valve defect.

In this case, the noises are heard especially well at the same points where the tones formed in the corresponding valves or sections of the heart are heard.

Auscultation of noises arising in the area of the mitral valve, both in case of its insufficiency (systolic noise) and stenosis of the atrioventricular orifice (diastolic noise) is performed at the apex of the heart.

Listening to noises arising in the area of the tricuspid valve is performed over the lower end of the sternum.

Auscultation of noises depending on changes in the aortic valve is performed in the second intercostal space on the right at the edge of the sternum. Here, a rough systolic noise associated with narrowing of the aortic orifice and a diastolic noise with aortic valve insufficiency are usually detected.

Listening to noises associated with vibrations of the pulmonary valve is carried out in the second intercostal space on the left at the edge of the sternum. These noises are similar to aortic ones.

Heart murmurs are heard not only in the specified areas, but also over a larger area of the cardiac region. They are usually well conducted along the blood flow. Thus, with narrowing of the aortic orifice, systolic murmur also spreads to large vessels, for example, the neck. With aortic valve insufficiency, diastolic murmur is determined not only in the second intercostal space on the right, but also on the left in the third intercostal space at the edge of the sternum, at the so-called V point; with mitral valve insufficiency, systolic murmur can be conducted to the left axillary region.

Depending on their intensity, noises are divided into 6 levels of loudness:

• 1st - barely audible noise that may disappear at times;
• 2nd - a louder noise, constantly detected in the heart;
• 3rd - even louder noise, but without tremors of the chest wall;
• 4th - a loud noise, usually with a tremor of the chest wall, also heard through the palm placed on the chest in the appropriate place;
• 5th - a very loud noise, heard not only over the heart area, but at any point in the chest;
• 6th - a very loud noise heard from the surface of the body outside the chest, for example from the shoulder.

Among the systolic murmurs, the following are distinguished: ejection murmurs, pansystolic murmurs and late systolic murmurs.

Systolic ejection murmurs are caused by blood flow through a narrowed aortic or pulmonic orifice, as well as by acceleration of blood flow through the same unchanged orifices. The murmur usually increases in intensity toward mid-systole, then decreases and ceases shortly before the second sound. The murmur may be preceded by a systolic sound. If aortic stenosis is severe and the contractile function of the left ventricle is preserved, the murmur is usually rough in timbre, loud, and accompanied by systolic tremor. It is transmitted to the carotid arteries. In the case of heart failure, the murmur may decrease significantly and become softer in timbre. Sometimes it is clearly audible at the apex of the heart, where it may be even louder than at the base of the heart.

In pulmonary artery stenosis, the systolic ejection murmur is similar to that in aortic stenosis, but is better heard in the second intercostal space on the left. The murmur is transmitted to the left shoulder.

In atrial septal defect, increased blood flow due to overfilling of the right side of the heart may result in a systolic ejection murmur on the pulmonary artery, but not louder than grade 3. At the same time, blood flow through the defect itself usually does not cause murmur.

Pansystolic murmurs are so called due to their long duration during the entire systole. This murmur usually has a slight increase in the middle or in the first half of systole. It usually begins simultaneously with the first tone. An example of such murmur is the auscultatory picture in mitral insufficiency. In this case, a pansystolic murmur is heard at the apex of the heart, conducted to the axillary region, reaching the 5th degree of loudness.

In case of tricuspid valve insufficiency, a pansystolic murmur is usually heard, it is heard best over the right ventricle of the heart at the left edge of the sternum in the fourth intercostal space.

In case of a ventricular septal defect, a long-lasting systolic murmur appears at the left edge of the sternum due to the blood flow from left to right. It is usually very rough in its timbre and is accompanied by a systolic tremor.

Late systolic murmurs occur in the second half of systole. Such murmurs are observed primarily in mitral valve prolapse. In this condition, there is an elongation or rupture of the chords, which leads to the development of prolapse of the mitral valve cusps and mitral insufficiency with the return of blood to the left atrium. The prolapse itself is manifested by a systolic tone in the middle of systole and mitral insufficiency with a systolic murmur after this tone.

Diastolic heart murmurs

Diastolic murmurs can be early, occurring after the second tone; mid-diastolic and late diastolic, or pre-systolic.

In aortic insufficiency, a blowing early diastolic murmur of varying intensity occurs in the second intercostal space on the right and at the V point. With a weak diastolic murmur, it can sometimes be heard only when holding the breath on exhalation, with the patient leaning forward.

In case of pulmonary valve insufficiency, which occurs when the valve is significantly dilated as a result of pulmonary hypertension, a diastolic murmur is heard in the second intercostal space on the left, which is called Steele's murmur.

Mitral stenosis typically manifests itself as a diastolic murmur, best heard at the apex. A characteristic manifestation of this defect is a presystolic murmur at the apex, arising as a result of left atrial systole.

Prolonged murmurs occur with an arteriovenous fistula, and are heard both in systole and diastole. Such murmurs occur with non-closure of the arterial (Botallo's) duct. They are most pronounced in the second intercostal space on the left and are usually accompanied by tremors. Pericardial friction murmurs are heard with inflammatory changes in its leaflets. This murmur is defined as louder, does not correspond to a strictly defined phase of cardiac activity, and is characterized by variability. The murmur sometimes increases with pressure from a stethoscope and when the body is tilted forward.

Combined heart defects (two or more valves) are quite common, as well as a combination of two defects of one valve. This leads to the appearance of several noises, the precise identification of which causes difficulties. In this case, attention should be paid to both the timbre of the noise and the area of its listening, as well as to the presence of other signs of a defect of one or another valve, in particular, changes in heart tones.

If there are two noises (systolic and diastolic) over the same orifice at the same time, which happens quite often, there is an assumption of double damage, narrowing of the orifice and valve insufficiency. However, in practice, this assumption is not always confirmed. This is due to the fact that the second noise is often functional.

Intracardiac murmurs can be organic, i.e. associated with anatomical changes in the structure of the valves, or functional, i.e. appear with unchanged heart valves. In the latter case, the murmur is associated with vibrations arising due to a faster blood flow, especially liquid blood, i.e. containing a smaller number of formed elements. Such a fast blood flow, even in the absence of narrowed openings, causes swirls and vibrations in intracardiac structures, which include papillary muscles and chords.

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Functional heart murmurs

Functional noises differ from organic noises in a number of features. They are more variable in sonority, especially when changing position and breathing. They are usually softer and quieter, no more than 2-3 degrees of loudness. Scratching and other rough noises are not functional.

Functional systolic murmur is quite common in children and young people. Among the causes of functional systolic murmurs associated with increased blood flow are feverish conditions and anemia, which lead to decreased blood viscosity and increased blood flow.

Diastolic murmurs are comparatively rarely functional; in particular, they occur in anemia in patients with renal failure and are most often heard at the base of the heart in the second intercostal space on the left at the edge of the sternum.

A number of physiological and pharmacological effects lead to changes in the auscultatory picture of the heart, which may have diagnostic value. Thus, with a deep inspiration, the venous return of blood to the right chambers of the heart increases, usually the murmurs arising in the right half of the heart increase, often with a splitting of the second heart sound. With the Valsalva maneuver (straining with a closed glottis), arterial pressure decreases, venous inflow to the heart decreases, which can lead to an increase in murmur in obstructive cardiomyopathy (muscular subaortic stenosis) and a decrease in murmur associated with aortic stenosis and mitral insufficiency. When moving from a lying to a standing position, venous inflow to the heart decreases, which leads to the just-described changes in the auscultatory picture in defects of the left half of the heart. When amyl nitrite is administered, blood pressure decreases and cardiac output increases, which increases murmurs in aortic stenosis and obstructive cardiomyopathy.

Factors that change the auscultatory picture of the heart

1. Deep breath - Increased venous return of blood to the heart and increased murmurs in right heart defects.
2. Standing position (quick standing up) - Decreases the return of blood to the heart and weakens murmurs in aortic and pulmonary artery stenosis.
3. Valsalva maneuver (straining with the glottis closed) - Increased intrathoracic pressure and decreased venous flow to the heart.
4. Inhalation of amyl nitrite or ingestion of nitroglycerin - Vasodilation - increase in ejection murmurs due to aortic or pulmonic stenosis.

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